Equalization by the pulse shape inverse of the input to the FRI processing in pulse based communications

ABSTRACT

Certain aspects of the present disclosure relate to a method for equalizing a pulse signal corrupted by a noise and by various channel effects for obtaining a signal based on the periodic-sinc pulse, which is suitable for Finite Rate of Innovation (FRI) processing applied at a receiver of a pulse-based communication system (e.g., an Ultra-Wideband receiver).

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present application for patent claims benefit of ProvisionalApplication Ser. Nos. 61/161,348 filed Mar. 18, 2009, 61/161,656 filedMar. 19, 2009, 61/224,808 filed Jul. 10, 2009, and 61/247,122 filed Sep.30, 2009, and assigned to the assignee hereof and hereby expresslyincorporated by reference herein.

BACKGROUND

1. Field

Certain aspects of the present disclosure generally relate to a wirelesscommunication and, more particularly, to equalization of a receivedpulse signal.

2. Background

Ultra-Wideband (UWB) communications are radio communications that use afrequency bandwidth larger than 500 MHz. In comparison to narrow-bandcommunications which rely on modulation of a carrier frequency, thelarge bandwidth of UWB communications allows sending signals withfeatures well-localized in time. If a signal is more localized in time,then it is more spread in frequency. This allows communications based onpulses, while information can be encoded in a distance between pulses(i.e., a Pulse Position Modulation: PPM), in a pulse amplitude (i.e., aPulse Amplitude Modulation: PAM) or in a pulse width (i.e., Pulse WidthModulation: PWM). One of the key advantages of pulse-based communicationis ability to precisely localize time of arrival of the information(i.e., arrival of the pulse).

A signal at the UWB receiver is typically based on a pulse signalcorrupted by stationary and non-stationary noise and by various channeleffects, wherein the pulse signal is different than a periodic sincshaped pulse. For example, the pulse signal can be based on asymmetrical low-pass pulse. On the other hand, a parametric Finite Rateof Innovation (FRI) processing that may be applied after the UWBprocessing requires an input signal based on the periodic-sine signal.Therefore, the received UWB pulse signal needs to be properly adjustedbefore being processed by the FRI block.

A method is proposed in the present disclosure to equalize the receivedUWB pulse signal in such a way to generate an output signal based on theperiodic-sinc function suitable for the subsequent FRI processing.

SUMMARY

Certain aspects provide a method for wireless communications. The methodgenerally includes receiving a signal transmitted over a wirelesschannel, wherein the received signal comprises a corrupted impulsesignal, performing a transform of a non-corrupted version of the impulsesignal and of a reference signal, and equalizing the received signalusing the transformed non-corrupted version of the impulse signal andthe transformed reference signal.

Certain aspects provide an apparatus for wireless communications. Theapparatus generally includes a receiver configured to receive a signaltransmitted over a wireless channel, wherein the received signalcomprises a corrupted impulse signal, a circuit configured to perform atransform of a non-corrupted version of the impulse signal and of areference signal, and an equalizer configured to equalize the receivedsignal using the transformed non-corrupted version of the impulse signaland the transformed reference signal.

Certain aspects provide an apparatus for wireless communications. Theapparatus generally includes means for receiving a signal transmittedover a wireless channel, wherein the received signal comprises acorrupted impulse signal, means for performing a transform of anon-corrupted version of the impulse signal and of a reference signal,and means for equalizing the received signal using the transformednon-corrupted version of the impulse signal and the transformedreference signal.

Certain aspects provide a computer-program product for wirelesscommunications. The computer-program product includes acomputer-readable medium comprising instructions executable to receive asignal transmitted over a wireless channel, wherein the received signalcomprises a corrupted impulse signal, perform a transform of anon-corrupted version of the impulse signal and of a reference signal,and equalize the received signal using the transformed non-corruptedversion of the impulse signal and the transformed reference signal.

Certain aspects provide a headset. The headset generally includes areceiver configured to receive a signal transmitted over a wirelesschannel, wherein the received signal comprises a corrupted impulsesignal, a circuit configured to perform a transform of a non-corruptedversion of the impulse signal and of a reference signal, an equalizerconfigured to equalize the received signal using the transformednon-corrupted version of the impulse signal and the transformedreference signal, and a transducer configured to provide an audio outputbased on the equalized received signal.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 illustrates an example wireless communication system inaccordance with certain aspects of the present disclosure.

FIG. 2 illustrates various components that may be utilized in a wirelessdevice in accordance with certain aspects of the present disclosure.

FIG. 3 illustrates equalization of a received pulse signal to match aperiodic sinc pulse shape signal in accordance with certain aspects ofthe present disclosure.

FIG. 4 illustrates example operations for equalization of a receivedsignal to match the periodic-sinc pulse shape signal in accordance withcertain aspects of the present disclosure.

FIG. 4A illustrates example components capable of performing theoperations illustrated in FIG. 4.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein, one skilled in the art should appreciate that thescope of the disclosure is intended to cover any aspect of thedisclosure disclosed herein, whether implemented independently of orcombined with any other aspect of the disclosure. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, the scope of thedisclosure is intended to cover such an apparatus or method which ispracticed using other structure, functionality, or structure andfunctionality in addition to or other than the various aspects of thedisclosure set forth herein. It should be understood that any aspect ofthe disclosure disclosed herein may be embodied by one or more elementsof a claim.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

An Example Wireless Communication System

The techniques described herein may be used for various broadbandwireless communication systems, including communication systems that arebased on a single carrier transmission. Aspects disclosed herein may beadvantageous to systems employing Ultra-Wideband (UWB) signals includingmillimeter-wave signals. However, the present disclosure is not intendedto be limited to such systems, as other coded signals may benefit fromsimilar advantages.

The teachings herein may be incorporated into (e.g., implemented withinor performed by) a variety of wired or wireless apparatuses (e.g.,nodes). In some aspects, a node implemented in accordance with theteachings herein may comprise an access point or an access terminal.

An access terminal (“AT”) may comprise, be implemented as, or known asan access terminal, a subscriber station, a subscriber unit, a mobilestation, a remote station, a remote terminal, a user terminal, a useragent, a user device, user equipment, or some other terminology. In someimplementations an access terminal may comprise a cellular telephone, acordless telephone, a Session Initiation Protocol (“SIP”) phone, awireless local loop (“WLL”) station, a personal digital assistant(“PDA”), a handheld device having wireless connection capability, orsome other suitable processing device connected to a wireless modem.Accordingly, one or more aspects taught herein may be incorporated intoa phone (e.g., a cellular phone or smart phone), a computer (e.g., alaptop), a portable communication device, a portable computing device(e.g., a personal data assistant), an entertainment device (e.g., amusic or video device, or a satellite radio), a global positioningsystem device, a headset, a sensor or any other suitable device that isconfigured to communicate via a wireless or wired medium. In someaspects the node is a wireless node. Such wireless node may provide, forexample, connectivity for or to a network (e.g., a wide area networksuch as the Internet or a cellular network) via a wired or wirelesscommunication link.

FIG. 1 illustrates an example of a wireless communication system 100(i.e., a Piconet 1) in which aspects of the present disclosure may beemployed. As illustrated, Piconet 1 may include a number of wirelessdevices 102 or “terminals” 1A-1E that can communicate with one anotherusing relatively short-range wireless links 104. In the illustratedexample, terminal 1E acts as a PNC for Piconet 1. Although illustratedwith five devices, it should be appreciated that any number of devices(i.e., two or more) may form a wireless personal area network.

Each of the terminals 102 in the Piconet 1 may include, among otherthings, a wireless transceiver to support wireless communication andcontroller functionality to manage communication with the network. Thecontroller functionality may be implemented within one or more digitalprocessing devices. The wireless transceiver may be coupled to one ormore antennas to facilitate the transmission of signals into and thereception of signals from a wireless channel. Any type of antennas maybe used including, for example, dipoles, patches, helical antennas,antenna arrays, and/or others.

The devices in the Piconet 1 may include any of a wide variety ofdifferent device types including, for example, laptop, desktop, palmtop,or tablet computers having wireless networking functionality, computerperipherals having wireless networking capability, personal digitalassistants (PDAs) having wireless networking capability, cellulartelephones and other handheld wireless communicators, pagers, wirelessnetwork interface modules (e.g., wireless network interface cards, etc.)incorporated into larger systems, multimedia devices having wirelessnetworking capability, audio/visual devices having wireless networkingcapability, home appliances having wireless networking capability,jewelry or other wearable items having wireless networking capability,wireless universal serial bus (USB) devices, wireless digital imagingdevices (e.g., digital cameras, camcorders, etc.), wireless printers,wireless home entertainment systems (e.g., DVD/CD players, televisions,MP3 players, audio devices, etc.), and/or others. In one configuration,for example, a wireless personal area network may include a user'slaptop computer that is wirelessly communicating with the user'spersonal digital assistant (PDA) and the user's printer in a short-rangenetwork. In another possible configuration, a wireless personal areanetwork may be formed between various audio/visual devices in, forexample, a user's living room. In yet another configuration, a user'slaptop computer may communicate with terminals associated with otherusers in a vicinity of the user. Many other scenarios are also possible.

Standards have been developed, and are currently in development, toprovide a framework to support development of interoperable productsthat are capable of operating as part of a wireless personal areanetwork (e.g., the Bluetooth standard (Specification of the BluetoothSystem, Version 3.0, Bluetooth SIG, Inc., April 2009), the IEEE 802.15standards, etc.). The IEEE 802.15.3c standard, for example, is a highdata rate wireless personal area network standard. In accordance withthe IEEE 802.15.3c standard, one of the terminals within a piconet isselected as a Piconet Coordinator (PNC) to coordinate the operation ofthe network. For example, with reference to FIG. 1, the device PNC 1Erepresents a PNC for the Piconet 1 in an IEEE 802.15.3c implementation.

As illustrated, PNC 1E may transmit a beacon signal 110 (or simply“beacon”) to other devices of Piconet 1, which may help the otherterminals within Piconet 1 synchronize their timing with PNC 1E. Thus,the beacon, typically sent at the beginning of every superframe,contains information that may be used to time-synchronize the terminalsin the piconet. Each terminal in the piconet, including the PNC, mayreset its superframe clock to zero at the beginning of the beaconpreamble. If a terminal does not hear a beacon, it may reset itssuperframe clock to zero at the instant where it expected to hear thebeginning of the beacon preamble (e.g., based on previous superframetiming).

In addition, terminals 102 can be communicating with one another in apeer-to-peer configuration. For example, the device DEV 1C may be incommunication with the device DEV 1D using the link 104. In peer-to-peerad hoc networks, devices (nodes) within range of each other, such as thedevices DEV 1C and DEV 1D in the network 100, can communicate directlywith each other without an access point, such as the PNC 1E, and/or awired infrastructure to relay their communication. Additionally, peerdevices or nodes can relay traffic. The devices 102 within the network100 communicating in a peer-to-peer manner can function similar to basestations and relay traffic or communications to other devices,functioning similar to base stations, until the traffic reaches itsultimate destination. The devices can also transmit control channels,which carry information that can be utilized to manage the datatransmission between peer nodes.

The communication network 100 can include any number of devices or nodesthat are in wireless (or wired) communication. Each node can be withinrange of one or more other nodes and can communicate with the othernodes or through utilization of the other nodes, such as in a multi-hoptopography (e.g., communications can hop from node to node untilreaching a final destination). For example, a sender node may wish tocommunicate with a receiver node. To enable packet transfer betweensender node and receiver node, one or more intermediate nodes can beutilized. It should be understood that any node can be a sender nodeand/or a receiver node and can perform functions of either sendingand/or receiving information at substantially the same time (e.g., canbroadcast or communicate information at about the same time as receivinginformation) or at different times.

FIG. 2 illustrates various components that may be utilized in a wirelessdevice 202 that may be employed within the wireless communication system100. The wireless device 202 is an example of a device that may beconfigured to implement the various methods described herein. Thewireless device 202 may be the PNC 1E or a terminal 102 in the Piconet1.

The wireless device 202 may include a processor 204 which controlsoperation of the wireless device 202. The processor 204 may also bereferred to as a central processing unit (CPU). Memory 206, which mayinclude both read-only memory (ROM) and random access memory (RAM),provides instructions and data to the processor 204. A portion of thememory 206 may also include non-volatile random access memory (NVRAM).The processor 204 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 206. Theinstructions in the memory 206 may be executable to implement themethods described herein.

The wireless device 202 may also include a housing 208 that may includea transmitter 210 and a receiver 212 to allow transmission and receptionof data between the wireless device 202 and a remote location. Thetransmitter 210 and receiver 212 may be combined into a transceiver 214.An antenna 216 may be attached to the housing 208 and electricallycoupled to the transceiver 214. The wireless device 202 may also include(not shown) multiple transmitters, multiple receivers, multipletransceivers, and/or multiple antennas.

The wireless device 202 may also include a signal detector 218 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 214. The signal detector 218 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 202 may alsoinclude a digital signal processor (DSP) 220 for use in processingsignals.

The various components of the wireless device 202 may be coupledtogether by a bus system 222, which may include a power bus, a controlsignal bus, and a status signal bus in addition to a data bus.

Ultra-Wideband (UWB) communications performed by the wireless system 100comprise radio communications that use a frequency bandwidth larger than500 MHz. In comparison to narrow-band communications which rely onmodulation of a carrier frequency, the large bandwidth of UWBcommunications allows sending signals with features well-localized intime. If a signal is more localized in time, then it is more spread infrequency. This allows communications based on pulses, while informationcan be encoded in a distance between pulses (i.e., a Pulse PositionModulation: PPM), in a pulse amplitude (i.e., a Pulse AmplitudeModulation: PAM) or in a pulse width (i.e., Pulse Width Modulation:PWM). One of the key advantages of pulse-based communication is abilityto precisely localize time of arrival of the information (i.e., arrivalof the pulse).

Finite Rate Sampling and Equalization in a Non-Ideal Setup

Finite Rate of Innovation (FRI) is a parametric processing approach thatmay be applied on signals received by a typical Ultra-Wideband (UWB)device, such as the device 202. The FRI processing may require an inputsignal based on the periodic-sinc function, while the received UWBsignal may be typically based on different types of pulses such as asymmetrical low-pass pulse signal. Because of that, the received UWBsignal may need to be properly adjusted (i.e., equalized) before beinginput into the subsequent FRI block.

Certain aspects of the present disclosure support a method forequalizing the received signal that comprises a corrupted impulse signaldifferent than the periodic-sinc signal to obtain a version of theperiodic-sinc signal suitable for the FRI processing. The proposedsolution relies on similarity between the pulse-shape and a PowerSpectral Density (PSD) of noise at the UWB receiver. The proposedequalization algorithm is based on a Discrete Fourier Transform (DFT) ofthe targeted periodic-sinc pulse-shape signal. It should be noted thatin the same time a whitening of the noise may be also achieved, which isa desirable feature of the proposed equalizer. The noise may be whitenedat the output of equalizer because the input white Gaussian noise isprocessed by the same filtering chain as the received signal.

FIG. 3 illustrates equalization of the received pulse signal applied toobtain the desired periodic sinc pulse shape based signal. FIGS. 3A-3Billustrate (in time and frequency domain, respectively) the idealdirichlet kernel shaped pulse (i.e., the periodic sinc signal) corruptedby a stationary noise and by the UWB transceiver, wherein corruptionintroduced at the UWB transceiver may be modeled using a B-spline shapedpoint-spread function.

FIG. 4 illustrates example operations 400 for equalization of thereceived signal to obtain a signal based on the periodic-sinc pulseshape in accordance with certain aspects of the present disclosure. At410, a signal transmitted over a wireless channel may be received at theUWB receiver, wherein the received signal may comprise a corruptedimpulse signal different than the desired periodic-sinc signal. At 420,the DFT or some other transform of a non-corrupted version (i.e., aversion without corruption from the wireless channel and noise) of theacquired impulse signal and the DFT of a reference signal may beperformed. The ideal version of the acquired impulse signal (i.e., thepulse without corruption from the wireless channel and noise) may beknown in advance at the receiver. The reference signal may be, forexample, the targeted periodic-sinc pulse shape signal.

At 430, the received signal may be equalized to obtain a version of theperiodic-sinc pulse shape signal by using the DFT of the non-corruptedimpulse signal and the DFT of the reference signal. In one aspect of thepresent disclosure, the DFT coefficient W[w] of the equalizer for anarbitrary frequency w of the received signal may be obtained as:W[w]=P ⁻¹ [w]·rect[w],  (1)where P[w] represents the DFT of the non-corrupted version of theacquired pulse signal, and rect[w] represents the DFT of the targetedideal periodic-sinc pulse shape signal.

A signal obtained by applying the equalizer defined by equation (1) onthe received signal may comprise a version of the periodic-sinc pulseshape signal. The equalized signal may be based on the idealperiodic-sinc pulse shape signal, and may be corrupted by the noise andby various channel effects.

As illustrated in FIG. 3C, the equalizer defined by equation (1) maycomprise deconvolution, i.e., multiplication of the received signal bythe inverse (in the Fourier domain) of the pulse signal. The proposedequalization may yield the periodic sinc pulse, as well as a whitenednoise for low frequencies. As illustrated in FIG. 3C, only a portion ofthe DFT coefficients of the equalized signal may be utilized for the FRIprocessing.

In another aspect of the present disclosure, equalization of thereceived pulse signal may be based on the Wiener deconvolution filtergiven as:

$\begin{matrix}{{{W\lbrack w\rbrack} = \frac{P^{*}\lbrack w\rbrack}{{{P\lbrack w\rbrack} \cdot {P^{*}\lbrack w\rbrack}} + {N\; S\;{R\lbrack w\rbrack}}}},} & (2)\end{matrix}$where P·[w] is a conjugate of P[w] and NSR[w] is a spectralnoise-to-signal ratio.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrate circuit (ASIC), or processor. Generally,where there are operations illustrated in Figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering. For example, blocks 410-430 illustrated in FIG. 4correspond to circuit blocks 410A-430A illustrated in FIG. 4A.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

As used herein, a phrase referring to “at least one of a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various operations of methods described above may be performed byany suitable means capable of performing the operations, such as varioushardware and/or software component(s), circuits, and/or module(s).Generally, any operations illustrated in the Figures may be performed bycorresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array signal (FPGA) or other programmable logic device(PLD), discrete gate or transistor logic, discrete hardware componentsor any combination thereof designed to perform the functions describedherein. A general purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thepresent disclosure may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in any form of storage medium that is knownin the art. Some examples of storage media that may be used includerandom access memory (RAM), read only memory (ROM), flash memory, EPROMmemory, EEPROM memory, registers, a hard disk, a removable disk, aCD-ROM and so forth. A software module may comprise a singleinstruction, or many instructions, and may be distributed over severaldifferent code segments, among different programs, and across multiplestorage media. A storage medium may be coupled to a processor such thatthe processor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The functions described may be implemented in hardware, software,firmware or any combination thereof. If implemented in software, thefunctions may be stored as one or more instructions on acomputer-readable medium. A storage media may be any available mediathat can be accessed by a computer. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage or othermagnetic storage devices, or any other medium that can be used to carryor store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Software or instructions may also be transmitted over a transmissionmedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition oftransmission medium.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

The invention claimed is:
 1. A method for wireless communications,comprising: receiving a signal transmitted over a wireless channel,wherein the received signal comprises a corrupted impulse signal;performing a transform of a non-corrupted version of the impulse signaland of a reference signal; and equalizing the received signal using thetransformed non-corrupted version of the impulse signal and thetransformed reference signal.
 2. The method of claim 1, wherein thereference signal comprises a periodic-sinc signal.
 3. The method ofclaim 1, wherein the transform comprises a discrete Fourier transform(DFT).
 4. The method of claim 1, wherein the impulse signal is corruptedby noise and by effects of the wireless channel.
 5. The method of claim1, wherein equalizing the received signal comprises: applying adeconvolution filter on the received signal in frequency domain.
 6. Themethod of claim 5, wherein an amplitude spectrum of the deconvolutionfilter is based on a discrete Fourier transform (DFT) of thenon-corrupted version of the impulse signal and a spectralnoise-to-signal ratio related to the received signal.
 7. An apparatusfor wireless communications, comprising: a receiver configured toreceive a signal transmitted over a wireless channel, wherein thereceived signal comprises a corrupted impulse signal; a circuitconfigured to perform a transform of a non-corrupted version of theimpulse signal and of a reference signal; and an equalizer configured toequalize the received signal using the transformed non- corruptedversion of the impulse signal and the transformed reference signal. 8.The apparatus of claim 7, wherein the reference signal comprises aperiodic-sinc signal.
 9. The apparatus of claim 7, wherein the transformcomprises a discrete Fourier transform (DFT).
 10. The apparatus of claim7, wherein the impulse signal is corrupted by noise and by effects ofthe wireless channel.
 11. The apparatus of claim 7, wherein theequalizer configured to equalize the received signal comprises: acircuit configured to apply a deconvolution filter on the receivedsignal in frequency domain.
 12. The apparatus of claim 11, wherein anamplitude spectrum of the deconvolution filter is based on a discreteFourier transform (DFT) of the non-corrupted version of the impulsesignal and a spectral noise-to-signal ratio related to the receivedsignal.
 13. An apparatus for wireless communications, comprising: meansfor receiving a signal transmitted over a wireless channel, wherein thereceived signal comprises a corrupted impulse signal; means forperforming a transform of a non-corrupted version of the impulse signaland of a reference signal; and means for equalizing the received signalusing the transformed non-corrupted version of the impulse signal andthe transformed reference signal.
 14. The apparatus of claim 13, whereinthe reference signal comprises a periodic-sinc signal.
 15. The apparatusof claim 13, wherein the transform comprises a discrete Fouriertransform (DFT).
 16. The apparatus of claim 13, wherein the impulsesignal is corrupted by noise and by effects of the wireless channel. 17.The apparatus of claim 13, wherein the means for equalizing the receivedsignal comprises: means for applying a deconvolution filter on thereceived signal in frequency domain.
 18. The apparatus of claim 17,wherein an amplitude spectrum of the deconvolution filter is based on adiscrete Fourier transform (DFT) of the non-corrupted version of theimpulse signal and a spectral noise-to-signal ratio related to thereceived signal.
 19. A computer-program product for wirelesscommunications, comprising a non-transitory computer-readable mediumcomprising instructions executable to: receive a signal transmitted overa wireless channel, wherein the received signal comprises a corruptedimpulse signal; perform a transform of a non-corrupted version of theimpulse signal and of a reference signal; and equalize the receivedsignal using the transformed non-corrupted version of the impulse signaland the transformed reference signal.
 20. A headset, comprising: areceiver configured to receive a signal transmitted over a wirelesschannel, wherein the received signal comprises a corrupted impulsesignal; a circuit configured to perform a transform of a non-corruptedversion of the impulse signal and of a reference signal; an equalizerconfigured to equalize the received signal using the transformednon-corrupted version of the impulse signal and the transformedreference signal; and a transducer configured to provide an audio outputbased on the equalized received signal.